Fixed
- Removed the explicit dependency on `urllib3` as we do not use it directly.
- Updated testing commands and dependency declaration to remove deprecated uses
of setuptool's `tests_require` configuration and `test` command.
Added
- Started active support for Python 3.7--3.9
Changed
- Dropped support for EoLed Python<3.6
Removed
- Python 2.7 compat code